Di(hydroperoxy)alkane Adducts of Phosphine Oxides: Safe, Solid, Stoichiometric, and Soluble Oxidizing Agents

Abstract

The di(hydroperoxy)alkane adducts of phosphine oxides 1-9, Ph PO⋅(HOO) CMe , Cy PO⋅(HOO) CMe , Ph PO⋅ (HOO) CMeEt, Cy PO⋅(HOO) CMeEt, Cy PO⋅(HOO) CEt , Cy PO⋅ (HOO) C(CH ) , Cy PO⋅(HOO) CMePh, (Ph P(O)CH CH P(O)Ph )⋅ ((HOO) CEt ) , and Ph P(O)CH P(O)Ph ⋅(HOO) CMe , respectively, are synthesized and fully characterized by H, C, and P NMR, and IR spectroscopies. Single crystal X-ray structures are reported for 3-9. Different one-pot synthetic pathways, starting from R P, R PO, R PO⋅H O, and R PO⋅H O are explored and discussed and a mechanism for the formation of the di(hydroperoxy)alkane adducts of phosphine oxides is suggested. The longevity of the adducts is tested by monitoring the oxidation of Ph P with quantitative NMR. The solubilities of the adducts in organic solvents are presented, and their applicability as stoichiometric oxidizing agents for the selective oxidation of sulfides to sulfoxides is reported.

Structures and Dynamics of Secondary and Tertiary Alkylphosphine Oxides Adsorbed on Silica

“…The torsion angle between the two P=Og roupsi s1 80.008.T his feature can be found in structures of other diphosphine dioxides. [31,40] In contrast to the structures of 1 and 2,t he P=Og roups of neighboring molecules of 5 are oriented parallel to each other. However,a gain no linear ···P=O···P=O··· moieties are formed, as found for Bu 3 PO, [22] and correspondingly,the P=Obond is comparatively short (1.489(2) ).…”

“…[21,22,38,39] Recently,w ed iscovered that phosphine oxidesa lso possess the unique ability to stabilize hydrogen peroxidea nd di(hydroperoxy)alkanes by forming strong hydrogen bonds. [21][22][23][39][40][41] All adducts exhibit one of two structural motifs, (R 3 PO·H 2 O 2 ) 2 and R 3 PO·(HOO) 2 CR'R" (R, R',R "= alkyl and aryl). [21][22][23][39][40][41] These stable, solid peroxide adducts are currently investigatedr egardingt heir potential as oxidizers.…”

“…[21][22][23][39][40][41] All adducts exhibit one of two structural motifs, (R 3 PO·H 2 O 2 ) 2 and R 3 PO·(HOO) 2 CR'R" (R, R',R "= alkyl and aryl). [21][22][23][39][40][41] These stable, solid peroxide adducts are currently investigatedr egardingt heir potential as oxidizers. [39][40][41] Here, we focus on the adsorption of the hitherto neglected secondary and tertiary alkylphosphine oxides, displayed in Figure 1, on silica.…”

“…[21][22][23][39][40][41] These stable, solid peroxide adducts are currently investigatedr egardingt heir potential as oxidizers. [39][40][41] Here, we focus on the adsorption of the hitherto neglected secondary and tertiary alkylphosphine oxides, displayed in Figure 1, on silica. As outlined above, unexpected dynamic phenomenao ft riphenylphosphine oxide can be observed by solid-state NMR spectroscopy.…”

“…In ordert oa void complications due to steric demandso farylo rc ycloalkyl substituents,w ee mployed phosphine oxides with linear methylene chains ( Figure 1). In order to avoid any complicating effects that could arise from the close proximity and directi nteractions of the P=Og roups in the diphosphine dioxides, as encountered for di(hydroperoxy)alkanea dducts of (Ph 2 PO) 2 CH 2 , [40] long methylene chains with 8a nd 14 CH 2 segments were incorporated betweent he two intramolecular phosphine oxide groups.…”